Ear: Hearing And Equilibrium

Front 1

What are the three parts of the ear?

Back 1

external, middle, inner

Front 2

What two sensory systems does the inner ear house?

Back 2

cochlea, vestibular apparatus

Front 3

What is hearing?

Back 3

the neural perception of sound energy

Front 4

What comprises a sound wave?

Back 4

traveling vibrations of air consisting of regions of high pressure caused by compression of air molecules alternating wiht regions of low pressure caused by rarefaction of air molecules

Front 5

What are the three ways in which sound is characterized?

Back 5

pitch (tone), intensity (loudness), timbre (quality)

Front 6

What determines pitch (tone)?

Back 6

frequency of vibrations

Front 7

The greater the frequency, the lower or higher the pitch?

Back 7

higher

Front 8

What determines the intensity, or loudness, of a sound?

Back 8

amplitude of the sound waves, or pressure differences between a high-pressure region of compression and a low-pressure region of rarefaction.

Front 9

the greater the amplitude, the softer or louder the sound is?

Back 9

louder

Front 10

In what unit is loudness measured?

Back 10

dB decibels

Front 11

What is the hearing threshold?

Back 11

the softest sound that can be heard

Front 12

What does every 10 dB indicate?

Back 12

A 10-fold increase in loudness.

Front 13

How is timbre measured?

Back 13

It depends on a sound's overtones, which are additional frequencies superimposed on the fundamental pitch or tone.

Front 14

Which part of the ear plays a role in sound localization?

Back 14

external ear

Front 15

What are the three main parts of the external ear?

Back 15

pinna (ear), external auditory meatus (ear canal), tympanic membrane (eardrum)

Front 16

What does the pinna do?

Back 16

Collects sound waves and channels them down the ear canal.

Front 17

Which part of the external ear can change the timbre of a sound?

Back 17

pinna

Front 18

Which part of the external ear contains modified sweat glands that produce cerumen (earwax)?

Back 18

ear canal

Front 19

Which part of the external ear is stretched across the entrance to the middle ear and vibrates when struck by sound waves?

Back 19

tympanic membrane

Front 20

What tube connects the middle ear to the pharynx (back of throat)?

Back 20

eustachian (auditory) tube

Front 21

What structure exposes the inside of the eardrum to atmospheric pressure?

Back 21

eustachian tube

Front 22

Is the eustachian tube normally open or closed?

Back 22

closed

Front 23

Where in the ear are tympanic membrane vibrations converted into fluid?

Back 23

the middle ear bones

Front 24

What are the three bones in the movable chain of small bones, or ossicles, in the middle ear?

Back 24

malleus, incus, stapes

Front 25

To what structure is the malleus attached?

Back 25

the tympanic membrane

Front 26

To what structure is the stapes attached?

Back 26

the oval window

Front 27

To what is the oval window an entrance?

Back 27

the fluid-filled cochlea

Front 28

When the chain of bones is set into motion, the oval window produces wavelength movements in the inner ear fluid at what frequency as the original sound waves?

Back 28

the same frequency

Front 29

What mechanisms increase by 20 times the force exerted on the oval window what it would be if sound wave struck oval window directly?

Back 29

the SA of tympanic membrane is much larger than oval window, the lever action of the ossicles provides an additional mechanical advantage

Front 30

What middle ear protective strategy provides protection only from prolonged loud sounds?

Back 30

the tympanic membrane tightens, thus limiting movement of the ossicular chain, diminshing transmission of loud sound waves to the inner ear.

Front 31

What is the name and shape of the hearing portion of the inner ear?

Back 31

cochlea, snail

Front 32

What are the three fluid-filled longitudinal compartments of the cochlea?

Back 32

cochlear duct (scala media), scala bestibuli, scala tympani

Front 33

What is the fluid within the scala vestibuli and scala tympani?

Back 33

perilymph

Front 34

What fluid does the cochlear duct contain?

Back 34

endolymph

Front 35

What is the region beyond the tip of the cochlear duct where fluid in upper and lower compartments of cochlea is continuous?

Back 35

helicotrema

Front 36

Which window seals the scala vestibuli from the middle ear?

Back 36

oval window

Front 37

Which window seals the scala tympani from the middle ear?

Back 37

round window

Front 38

To what window is the stapes attached?

Back 38

oval

Front 39

What membrane separates the cochlear duct from the scala vestibuli?

Back 39

vestibular membrane

Front 40

What membrane separates the cochlear duct from the scala tympani?

Back 40

basilar membrane

Front 41

What membrane bears the organ of Corti?

Back 41

basilar membrane

Front 42

What is the sense organ for hearing?

Back 42

organ of Corti

Front 43

What organ contains the auditory hair cells?

Back 43

organ of Corti

Front 44

What are the receptors for sound?

Back 44

auditory hair cells

Front 45

How many rows of inner and outer hair cells are there aligned in four parallel rows along basilar membrane?

Back 45

one row inner, three rows outer

Front 46

What are stereocilia?

Back 46

Actin-stiffened microvilli that protrude from the surface of each hair cell

Front 47

What kind of receptors are hair cells?

Back 47

mechanoreceptors

Front 48

What organ do the stereocilia contact?

Back 48

tectorial membrane

Front 49

As the stapes causes the oval window to bulge inward, how is pressure dissipated? 2 ways.

Back 49

1. displacement of the round window 2. deflection of basilar membrane

Front 50

Which pathway is associated with sound reception?

Back 50

deflection of basilar membrane

Front 51

Describe the shortcut that pressure waves of frequencies associated with sound reception take.

Back 51

Vibration of oval window. Shortcut from scala vestibuli through basilar membrane to scala tympani. Triggers activation of receptors for sound by bending the hairs of hair cells as the organ of Corti on top of the vibrating basilar membrane is displaced in relation to the overlying tectorial membrane.

Front 52

Which end of the basilar membrane vibrates best with high-frequency pitches?

Back 52

the narrow, stiff end nearest the oval window

Front 53

The wide, flexible end of basilar membrane near helicotrema vibrates best with which frequency pitches, high or low?

Back 53

low

Front 54

Which are the hair cells that "hear," inner or outer?

Back 54

inner

Front 55

What action causes the opening and closing of gated cation channels in the hair cell?

Back 55

stereocilia of inner receptor cells contact the stiff, stationary tectorial membrane. There's a back and forth mechanical deformation of the hairs that causes the opening and closeing of channels and thus the depolarizing and hyperpolarizing potential changes at the same frequency as the original sound stimulus.

Front 56

What are tip links?

Back 56

CAMs (cell adhesion molecules) that link the tips of stereocilia in adjacent rows.

Front 57

What is unusual about the ion movement of K in constrast to ECF elsewhere?

Back 57

There is a higher concentration of K+ outside the cell than inside the hair cell, so when cation channels are opened, K + enters cell. Entering K depolarizes the hair cell.

Front 58

Does the hair cell depolarize or hyperpolarized when stereocilia bend toward tallest member?

Back 58

depoliarize

Front 59

When stereocilia bend toward tallest member, do tip links stretch and open channels or slacken and close channels?

Back 59

stretch and open channels

Front 60

What happens to the tip links, K + action, Ca2+ channel action, and neurotransmitter action when stereocilia bend away from tallest member?

Back 60

tip links slacken and close channels, no K enters, hair cell hyperpolarizes, Ca channels close, no neurotransmitter is released, no action potentials occur.

Front 61

Do photoreceptors and hair cells undergo action potentials?

Back 61

no

Front 62

What is electromotility?

Back 62

outer hair cells actively and rapidly change length in response to changes in membrane potential.

Front 63

Do outer hair cells lengthen or shorten on depolarization?

Back 63

shorten

Front 64

Do outer hair cells lengthen or shorten on hyperpolarization?

Back 64

lengthen

Front 65

How do outer hair cells affect inner hair cells?

Back 65

Outer hair cells enhance response of inner hair cells, making them sensitive and discriminatory in pitch and intensity

Front 66

How is the auditory cortex mapped?

Back 66

according to tone

Front 67

How do afferent neurons that pick up auditory signals from the inner hair cells exit the cochlea?

Back 67

via the auditory nerve

Front 68

Where are the most notable synapses en route on the neural pathway between the organ of Corti and the auditory cortex?

Back 68

in the brain stem and medial geniculate nucleus of the thalamus.

Front 69

What role does the thalamus play in transmission of sound signals upward?

Back 69

it sorts and relays the signals upward

Front 70

How are auditory signals different than visual signals in the pathway?

Back 70

Auditory signals from both ears are transmitted to both temporal lobes because the fibers partially cross over in brain stem.

Front 71

What are the two components of the vestibular apparatus?

Back 71

semicircular canals and otolith organs

Front 72

What does the vestibular apparatus do?

Back 72

important for sense of equilibrium and coordinating head movements with eye and postural movements

Front 73

are the components of the vestibular apparatus and the cochlea containing endolypmh and surrounded by perilymph?

Back 73

yes

Front 74

What are the two types of deafness?

Back 74

1. conductive deafness 2. sensorineural deafness

Front 75

When does conductive deafness occur?

Back 75

When sound waves are not adequately conducted through the external and middle portions of the ear to set the fluids in the inner ear in motion.

Front 76

What are possible causes of conductive deafness?

Back 76

Physical blockage of the ear canal with earwax, rupture of the eardrum, middle ear infections with accompanying fluid accumulation, or restriction of ossicular movement because of bony adhesions between the stapes and oval window.

Front 77

What part of the ear causes sensorineural deafness?

Back 77

inner ear

Front 78

What happens in sensorineural deafness?

Back 78

Sound waves are transmitted to the inner ear, but they are not translated into nerve signals that are interpreted by the brain as sound sensations.

Front 79

What are the three parts of the ear that could contain the defect that causes sensorineural deafness?

Back 79

1. organ of Corti 2. the auditory nerves 3. in the ascending auditory pathways or auditory cortex

Front 80

What is the scientific name for partial hearing loss?

Back 80

neural presbycusis

Front 81

What is one of the most common causes of neural presbycusis?

Back 81

A degenerative, age-related process that occurs as hair cells wear out with use.

Front 82

Which hair cells are most vulnerable to destruction, ones that process high or low frequency sounds?

Back 82

high frequency sounds

Front 83

Are hearing aids more helpful in sonsorineural deafness or conductive deafness?

Back 83

conductive deafness

Front 84

How is the vestibular apparatus important for equilibrium?

Back 84

It detects position and motion of the head

Front 85

What part of the ear contains the vestibular apparatus?

Back 85

inner ear

Front 86

The vestibular apparatus's semicircular canals and otolith organs lie within a tunneled-out region of what bone?

Back 86

temporal bone

Front 87

What are the two structures of the vestibular apparatus?

Back 87

1. semicircular canals 2. otolith organs

Front 88

How is the vestibular apparatus similar to the organ of Corti?

Back 88

both contain hair cells that respond to mechanical deformation triggered by specific movements of the endolymph.

Front 89

What do the semicircular canals detect?

Back 89

rotational or angular acceleration or deceleration of the head.

Front 90

What detects motion when starting or stopping spinning, somersaulting, or turning the head?

Back 90

semicircular canals

Front 91

How many semicircular canals are in each ear?

Back 91

3

Front 92

What structure houses the receptor hair cells of each semicircular canal?

Back 92

a ridge in the ampulla, a swelling at the base of the canal

Front 93

In what structure are the hair cells of the semicircular canal embedded?

Back 93

cupula, which protrudes into the endolymph within the ampulla.

Front 94

Does the cupula sway in the direction or opposite to fluid movement?

Back 94

in the direction, like seaweed swaying in the tide

Front 95

As you start to move your head, what structures move along with it?

Back 95

canal and ridge of hair cells embedded in cupula

Front 96

In which direction is the endolymph in the canal moving at the start of head motion

Back 96

opposite to head motion direction, bending the sensory hairs embedded in it.

Front 97

What are the two components of a vestibular hair cell?

Back 97

kinocilium and stereocilia

Front 98

Are both auditory and vestibular hair cells linked by tip links?

Back 98

yes

Front 99

Do the hair cells depolarize or hyperpolarize when its stereocilia are bent toward the kinocilium?

Back 99

depolarize

Front 100

What forms the vestibular nerve?

Back 100

hair cells form a chem. mediated synapse with terminal endings of afferent neurons whose axons join with those of the other vestibular structures

Front 101

With what nerve does the vestibular nerve unite to form the vestibulocochlear nerve?

Back 101

the auditory nerve from the cochlea

Front 102

Does depolarization increase the release of neurotrasnmitter from the hair cells?

Back 102

yes

Front 103

What do the otolith organs provide info. about?

Back 103

head position relative to gravity and changes in rate of linear motion. aka static head tilt and moving in a straight line.

Front 104

What are the two otolith organs?

Back 104

utricle and saccule

Front 105

Between what two inner ear structures are the utricle and saccule located?

Back 105

in a bony chamber between the semicircular canals and cochlea

Front 106

What kind of crystals compose the otoliths?

Back 106

calcium carbonate

Front 107

What are two motions that can activate the utricle?

Back 107

1. change in head position, like head tilt 2. horizontal linear acceleration

Front 108

What kind of movement does the saccule respond to?

Back 108

tilting of the head away from a horizontal position (like getting up from bed), vertically directed linear acceleration and deceleration (jumping up and down, riding an elevator)

Front 109

To what nuclei are the signals arising from the components of the vestibular apparatus carried to?

Back 109

through the vestibulocochlear nerve to the vestibular nuclei

Front 110

In what structure of the CNS is the vestibular nuclei located?

Back 110

brain stem

Front 111

Are signals from vestibular apparatus carried to the cerebellum?

Back 111

yes

Front 112

What kind of vestibular information is integrated with input form eyes, skin surface, joints and muscles, in the vestibular nuclei?

Back 112

1. balance and posture maintenance 2. external eye muscle control 3. motion and orientation perception